MTK

Does anyone know how thick or viscous the mixed AdTech epoxy is or how that compares to Pro Set 125/229?

Dave, I just finished a couple molds and several laminates using EZLam. It's okay, with a good pot life and final properties, but thicker than ProSet, meaning a bit more difficult to use. BUT Pro Set is expensive material and I am looking for something with similar processing characteristics that doesn't break the bank

MattK

MTK

I also have a quart kit of the 300/21 J.Greer epoxy coming tomorrow. Price is certainly right on this material but don't have any idea how it will process.

MattK

diggs_74

I would put the AdTech right about the same as the EZLam, maybe a bit less viscous but not much.. This is totally by memory mind you. I haven't used EZLam in a while..

daven

My Feedback: (1)

let us know how it goes Matt, I have used ProSet also, and do like it, just not going to pay that much.

aeroanalysis

You're going to be happy with the J.Greer. Wets out like water.

tony-howard

My Feedback: (224)

How's its resistance to sag on vertical surfaces?

MTK

Thanks.

Here's what JGreer sent me:

AeroMarine Cycloaliphatic “Non Blushing� Clear Epoxy #300/21

AeroMarine 300/21 is a clear, low viscosity cycloaliphatic epoxy system is primarily used for laminating, coating, and casting small objects. It contains no VOCs, and is relatively moisture insensitive.

Seven advantages of cycloaliphatic epoxies vs. conventional epoxies are:
• Resistance to amine blush
• Better sunlight and UV resistance
• Useable in damp conditions and high humidity
• Excellent gloss and clarity
• Excellent chemical resistance
• Cures well even at low temperature
• Less need for sanding between coats


Uses include:
• Laminating boats and aircraft using fiberglass, carbon fiber, or Kevlar cloth
• Casting small objects
• Building “stitch and glue� boats
• Potting electronic assemblies
• Potting specimens for measurement
• Coating wood and concrete
• Bonding and adhering wood, metal, concrete, and most plastics
• Flooring
• Pouring countertops and bartops

The mix ratio is a simple 2:1 by either weight or volume. AeroMarine 300/21 is a thin, clear liquid. It has a working life of about 30 minutes, and sets hard in a few hours.


Specifications:

Mixed viscosity: 600cps
Color: Clear
Work life: 30 minutes@70F
Cure time: 24 hours@70F
Shore D Hardness 80-85
Shear strength: 2500 psi
Tensile Strength 10,500 psi
Flexural strength: 17,500 psi
Modulus of elasticity: 5.7 x 106 psi

Directions for use:

Mix 2 parts AeroMarine 300 Resin to 1 part AeroMarine 21 hardener. To avoid excess exotherm, mix small batches until you are familiar with using this material. If laminating with cloth, it is best to apply subsequent layers within 18 hours.
For industrial or professional use only.
www.jgreer.com




Best practices when using epoxy resin



Never mix less than about 3 ounces of product. When manufacturers design and test their resins they normally write the specifications for 100 gram batches, which is about 3 ounces.
There are two bad things that can happen when mixing a smaller batch. Because the sample is small, it is much more difficult to get the mix ratio correct. Also, these mixtures are exothermic, meaning that they generate heat in order to cure. A tiny batch does not generate enough heat to cure the resin properly.

Avoid mixing a large batch- At least until you are familiar with the product. The larger the batch, the more exotherm or heat is generated in the cure cycle. If you are casting a large part, consider mixing small batches to make the process more manageable. Thickness of the pour also affects the exotherm and cure speed. 3/8� is about the maximum thickness to pour most epoxies.

Don’t vary the mix ratio- Old style polyester resins were catalyzed with a chemical called MEKp. You could vary the mix ratio to get different reaction speeds. Modern epoxies, polyurethanes, and silicones are different. They don’t use a true “catalyst�, but have a different kind of reaction method. Varying the mix ratio usually results in a mess.

Consider mixing everything twice- especially if you are a beginner. Mix the two components together, then transfer the mixture to another container and mix them again. The theory is that the liquids clinging to the sides and bottom of the containers don’t get mixed well. By transferring the mixture to another container, you are assured that everything is well mixed. Do not try to mix expanding foam twice because it begins to set in less than a minute.

Mix in plastic containers. Paper cups contain moisture which may adversely affect the resin, especially polyurethanes. Avoid waxed paper cups.

Avoid mixing with drill motors. Mixing with an electric drill can cause a few problems. Frequently they don’t get into every corner of the mixing container. Also, if they spin too fast they can generate friction in the resin causing it to exotherm out of control resulting in premature curing. Powered mixing also can generate a lot of air bubbles.


Storage- Epoxy hardeners usually last forever. Epoxy resins, however, tend to freeze even at fairly high temperatures, sometimes into the fifty degree Fahrenheit range. If allowed to freeze, “epoxy ice� can form in the container. It usually looks like swirls of white stuff suspended in the resin. It can be reconstituted by warming at 120F for a couple of hours- or you can use the “non-ice� part of the epoxy.

Spraying- Epoxies don’t spray well- they tend to run off vertical surfaces when sprayed. Addition of Cabosil will eliminate the run-off, but the epoxy turns a whitish color.

Clean-up- We use aerosol carburetor cleaner to clean up spills and messes. Otherwise just about any solvent will work, including acetone, MEK, toluene, xylene, and lacquer thinner. Avoid regular paint thinner (mineral spirits). To clean hands use “Fast Orange� hand cleaner available in automotive supply stores.

Thinning- Thinning is not recommended for most applications. There are very few exceptions. The most common acceptable use of a thinner is when using epoxy to penetrate wood. In this case about 10% is a good amount of thinner to use. Keep in mind that thinners are flammable, so spread the epoxy promptly after thinning to keep the exothermic heat from building up. Use the same thinners listed in the Clean-up section above.

Test- Always make a test to determine the feasibility of your process. There are many unforeseen factors that can affect the outcome of your project. Running a controlled test may be inconvenient, but it can make the “Learning Curve� of processing these products much easier.

CloudyIFR

I had asked John Greer about mix ratios as they were volume and it's much easier for me to mix by weight.

Here's what he wrote:
They have about the same specific gravity, so 2:1 is fine by either weight or volume.
I prefer to err on the side of less hardener and have personally had excellent results at 3 resin to 1 hardener.
John

End Quote.

Curtis
www.TailwindGliders.com

aerofly0610

you guys rock! thanks for all the info!!!

MTK

First couple batches are curing right now. The epoxy is not as thin as Pro Set but is slightly thinner than EZLam.

It wets out very nicely, and even though it's supposed to be 30 minute pot life, mine was workable at around 45 minutes in a 60 deg basement. If it's as strong as advertised, it will work fine. The price is terrific...half the cost of ProSet and the yield is greater at 1 1/2 quarts vs 4 1/2 pints

MattK

Scorpion Racing

Matt, was there any hazardous material charges on your shipment? I love MGS resin, but it now will cost me $160 haz-mat (resin & hardener have to ship separately!) PLUS shipping charges and I won't do that! I actually had Wicks bring it to Sun-n-fun last year in there exhibition truck, and they didn't charge me for that(good people at Wicks ). If the J Greer is comparable in strength and color clarity, I will give it a shot too. I will be needing a couple gallons for a couple of projects I got in the works...

Thanks,

MTK

Scott,

For the small quantity of 1 1/2 quarts, there was no Haz Mat charge. Just 13$ for S&H

I also looked at he 1 1/2 gallon quantity and although S&H jumped a bit, it didn't look like Haz Mat charge to me

You may want to give them a call and find out. But I'd start with the small quantity first to make sure it cures to your satisfaction. 29$ is cheap price to pay. Cycloaliphatic hardener (as opposed to amine) takes more time to fully cure in my experience. Clarity is terrific. Cycloaliphatic is much more light stable

MattK

Oh BTW- use the reccommended ratio of 2 :1 or 1:1 depending on the hardener you get. Going to 3:1 as one posting stated results in a resin rich finshed good which is resilient but not quite as firm as I 'd like to see. The fact that you can either use volume or weight as the measure is very convenient.

Props4ever

I have been using Aeropoxy for a while now, i have fiberglassed 90% of my 9'ws S Constellation model with this epoxy directly over foam core structure, both wings and fuselage. Arrow's fabrication on aft missing fuselage section (In the back ground of the picture below). Worked very well with me. I used 4oz and 6oz weave cloth and had no problems as long as mix was done right!. It's 3:1 ratio mix by weight but i just mixed it by eye and got gr8 feel about it in initial tests pieces and way i went.

I will be using same epoxy on my balsa sheeted foam core wings and fin of my 1:8 Avro Arrow model in next couple of days, all should go well. With epoxy resins right mix is the key, you can't add extra hardener if you feel it will harden faster!, it just doesn't work that way.

I use 2.25lbs kits at a time, it costs $37 bucks for small the kit, kind bit pricey but well worth it.
It's nice to work with as it's not watery type or hard type, i really like it. I use PR 2032 resin and PR 3630 hardener, this is 30mins hardener and give enough working time for average modeler.

Most likely most cheap resins sold at most every day hardware stores are poly resins....
Epoxy resins are bit expansive but results are great....


Hope this helps...


Cheers,
Sam

charlieoneseven

MAS epoxy is great stuff, non blush, slow cure, no heat build up in the cup or on thick layups on tooling.
I have a gallon of resin and half gallon of hardner with pumps instead of the caps. one or ten pushes on the top of each goes in the same mixing cup.
An hour or more of working time, overnite cure ambiant. about 3 days full cure. No odor and thin enough for wetting out the heaviest cloth.

CloudyIFR

Sam,

Beautiful Connies!

This is way off topic but you might be interested in these two short articles.

http://helenair.com/news/local/artic...cc4c03286.html

http://evergreenmuseum.wordpress.com...lation-update/

Curtis
Montana

Props4ever

Thanks Curtis,

That's another great save of the ole girl and a great story itself. I have read about that particular EC-121 on www.conniesurviors.com , It sure will be made ready for flight once again since Evergreen museum have enough resources to do so.

My 1/14th S Connie is the first one, Mats livery one belongs to my friend Carl Bershaber. It's a lot bigger then my bird but it's one beautiful model.


Sam

MTK

I've build a couple molds and pulled a few parts using the JGreer epoxy and it appears pretty good all around. Working time is a bit short at about 35-40 minutes but for small jobs that's all you need anyway. It's still a bit soft after 24 hours but plenty firm to demold.

I post cure for max firmness.

An inexpensive alternative works for me

MattK

CloudyIFR

Matt,

What's your post cure procedure? In other words how long do you wait till putting it under heat and then how long are you leaving it there?

Thanks
Curtis

MTK

Curtis,

I don't believe its anything special. After I trim the product once de-molded, I put the critical pieces in the chamber at 130F for 24 hours. Critical parts means things that will bear weight and shock like landing gear or propellers. Maybe higher temp and more time will produce better results or maybe it won't. This schedule seems to work fine for the things I do

I don't bother to post cure things that won't see much load.

MattK

Centralrchobbies

My Feedback: (7)

Does the jGreer epoxy dry as hard as West System? It would be nice as it is alot cheaper than West System.

MTK

I have not tested the modulus of the cured epoxies, neither WestSystems nor JGreer. Include in that my personal favorite, Pro Set, whch is also made by Gougeon Bros as West Systems is.

JGreer cured appears to me to be very similar but if tested on an extensometer it might be different. It may not be different enough to make a difference in actual application in model use. Tesnile strengths of thetwo types of epoxies are reported to be very similar....again I have not tested these to get stress-strain curves. Maybe one of these days I build a bunch of coupons and do the testing myself so I'll know for sure

MattK